Means for acidizing gas wells



E. S. VILLINES MEANS FOR ACIDIZING GAS WELLS April 17, 1951 2 Sheets-Sheet l April 17, 1951 E. s. vlLLlNES MEANS FOR ACIDIZING GAS WELLS Patented Apr. 17, r1951` UNITED STATES PATENT; OFFICE* MEANS FORAonnzntge.'GAS WELLsf Elbertsvillines, Lakimflians. Y. Applicationnugustis. 1947, serial No. 767,409 1 claim..v .(01. 16s-1 1)y This invention vrelates .to animprovedappara- 1.

tuszfor .acidizing gaszwells.

It is an object of this invention to provide-apparatus for an improved procedure `for acidizf, ing. vrgas `or oil wells inwhich a swab-packer; on a iiexible supportris introduced into Va wellyanA acidizing `solution isy introduced throughr perforations in the casing above the swabvpacker and the swab packer is thenfremoved.

A broad embodiment :of my invention comprises introducing anzacidizing tool by means of a leting-in-tool and cable into a gas well, disengaging and withdrawing said letting-in tool, shutting in Asaid well, introducingnacid.through casing perforations-above saidacidizing tool, and then removing said acidizing tool.

In acidizinggas well formations to increase the flow of natural gas, it is sometimes necessary to introduce dilute hydrochloric acid solution through perforations inthe well casing to reach the gas producing horizons. This is especially true Where the well is cased to the bottom, or through thegaszproducing horizon, and then gun perforated opposite the gas bearing strata. The usual practice is to run pointrbelow the perforations; set the plug, acidize,

and thenA goin with toolsand 'drill 'out the bridge. plug whichlli's a time consuming: and expensiveV operation. Another means Loften employed is to i run a packerzon a .tubing .stringgand settingsaid.

packer below the perforations through which it is desired to treat the gas producing formation by introducing a dilute hydrochloric acid solution. Running packers on tubing is also expensive and time consuming.. A more desirable method and means to accomplish the above and reduce the time and expense factors is to use a combination swab-packer-tool that will presently be described in light of the accompanying drawings.

Figure 1 is a vertical sectional view showing the selective acidizing tool being run into a gas well.

Figure 2 is an enlarged vertical sectional view showing the parts of the acidizing tool in detail and their relation to each other.

Figure 3 is a fragmentary view partly in section and partly in side elevation showing the connection between the letting-in tool andthe tool body. n

Figure 4 is a cross-section of Figure 3 taken along the line 4 4.

Figure 5 shows the tool set in position in the well bore, and the well closed in and lled with uid.

a, bridge plug t0 la,

I Figure shows the'tool beingvwithdrawn:from: the'well. 1 f

casing 6. 1 With valveeandits` supporting mem-e..

ber easily detachablefromcasing .8, and` of splitk construction of the -typelwelllknown inthisart, the' tool `may easily be introduced. into4 the. casing'ii'.A On-the end-'of line:2, a rope socket 1 is firmly securedlintofwhich. is screwed. the letting. l

in tool 8, whichis coupled: to :the selective acidiZ'.-. ing tool comprising parts` 9 through; 24iinclusive, and shown in detailin Figure 2.

Referring toFigure r2, any1..V fluid; inthe *hole such Aas gas, water,`L spent .acidsolutioitY .or petroleumfV or itsziractions.willoiierconsiderable resist*-A ancej to flow-l pastathe.l cups,y I 9.1;, .Therefore these fluids.- are directed. .through;the. perforations .23'.5l inthe length rof tubing. 23,;'and:z.caused-to new... upward..throughsthextool to .ballvyalve I5 which: is raised from-seat ll 6 and .thezuidapasses through perforationszzld in cagexl toemergeabove cups;

I9. When. .the;tool reachesbottom'it vis raised slightly and dropped. ;Theweight,of. rope socket 1 plus letting-in tool 8 andganyother tools,such asjars-andzstemfis suiiicientrto rbend pin I8 into grooves Il so that rope socket 1 and letting-in too18 may be withdrawn from serrated sub l2, of the selective acidizing tool, as shown in Figures 3 and 4. Y

Still referring to Figure 2, it is to be seen that letting-in tool 8 has a hole drilled near the bottom to match a similar hole in sub I2; the hole in tool 8, however, does not go all the way through the body vof 8. Pin I8 is of soft material and is held in place by pin 9 which ts in a hole drilled at right angles through the lower portion of 8 such that it intersects the hole for pin I0 on the center line to hold pin l0 in position.

In Figures 3 and 4, after the entire assemblyr has been dropped, the weight of socket 1 and letting-in tool 8 and jars and stem bends the ends of I0 down into the milled grooves Il, thus disengaging the letting-in tool 8 from the sub I2, and leaving the selective acidizing tool in the hole. Rope socket 1, and letting-in tool 8 and jars and stem are now withdrawn from the well bore as shown in Figure 5. The principle parts of the selective acidizing tool are (refer to Figure 2) serrated sub I2, which is securely joined to cage I3, with perforatons I4, ball I and seat I6. A mandrel tube I1 is screwed into the bottom of I 3 and spacer tube I8 fixes the position of the packer cup I9, which is of rubber or similar suitable material and its reinforcing metal cup 20. As many of these cup combinations may be spaced on mandrel I1 as desired by using a suitable number of spacers I8, all locked securely by collar 2|. The tubing anchor, comprised of collar 2|, tubes 22, 23 and bull plug 24, is made of such length that the packer will seal olf the bottom of the well from the perforations 25 which are opposite the gas zone.

In Figure 5 the selective-acidizing tool is Set g in a Well bore below the perforatins 275. vValve 4 is closed and one valve 5 is closed-whichisf connected to the line running to the mud pit,

or blow down pipe. nected to a pump (not shown) and acid solution is introduced in the well bore when the cups I9 seal the upper portion of the well from the lower portion such that the acid is forced into theY gas strata through perforations 25. The acidv is followed by a water fiush in suioient quantity to clear the casing of the acid solution.v A part of this water is now swabbed from the hole, and the selective acidizing tool is retrieved as follows:

A fishing tool 26 is attached to rope socket 1, see Figure 7. The shing tool shown is well known in the art. The angular mouth 28 guides the body 26 over serrated sub I2 such that slips 21 engage sub I2, the internal surface 29 of body 8 is inclined at an angle and so proportioned that slips 21 move out horizontally as they are moved upward. As the overshot or fishing tool takes hold the slips engage the serrations on sub I2, thus The other valve 5 is con`' 4 a tool .body having an upwardly facing packet cup on its outer surface for sealing engagement with the wall of a well bore upon existence of pressure above said packer cup greater than the pressure below such cup, a longitudinal passage through said body, a tubing anchor depending from said body for supporting said body above the bottom of a Well, perforations above and below said packer cup communicating with said passage to permit flow of gas upwardly through' said `passage from below said packer cup during lowering of said apparatus into a gas well, a one-way valve in'said passage preventing ow of fluid down- V:wardly through said passage, a cable for lowering y said body intora gas Well, releasable means for connecting said ca-ble to said body, said means Ycomprising an upwardly extending member on said body having a transverse opening therethrough, the outer ends of said transverse opening terminating in vertical grooves in the side walls of said upwardly extending member, said p grooves extending downwardly from said ends of rmly securing the selective acidizing tool to the fishing tool 26. are such that the slips 21 cannot fall out of the beveled mouth 28, before engaging sub I2.

As the tool is removed from the well, see Figure 6, the swabbing action of the cups I9 remove the excess fluid above the tool and lower the pressure across the perforations 25 so the spent acid solutions tend to flow into the Well bore, thus cleaning the newly created porosity and 4vpermeability developed by the acid treatment.

Other modifications may be made scope of the following claim:

I claim as my invention:

Apparatus for acidizing gas wellscomprising Within the The proportions of 26 and 21 said opening, a letting-in tool secured to said cable, said letting-in tool having a central cavity therein for reception of said upwardly extending member, and a bendable pin extending through said opening in said upwardly extending member and having its outer ends extending into the side walls of said cavity to support said body member from said letting-in tool, said bendable pin being capable of having its outer ends bent downwardly into said grooves and out of holding engagement with the side walls of said cavity upon dropping said body and letting-in tool a short distance to cause said tubing anchor to strike the bottom of a well.

ELBERT S. VJLLINES.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Date 

